A known scalp vein liquid injection device comprises a generally butterfly-shaped plastic needle holder element fixedly attached to a rear end portion of a hollow injection needle and having a pair of flexible side strip portions laterally projecting in opposite directions from the rear end portion of the needle. The rear end portion of the injection needle axially projects rearwardly from the needle holder element thus configured and is detachably fitted into a foremost end portion of a longitudinal passageway in a flexible plastic tube. The flexible plastic tube in turn is detachably fitted at the rear end thereof to an adapter element to be fitted to a front tip portion of a syringe barrel or to a leading end portion of a liquid conducting tube in a drip chamber liquid dispensing system. When in inserting the injection needle of such a scalp vein liquid injection device into a vein in, for example, a patient's arm, the flexilbe side strip portions of the needle holder element are bent into erect positions by operator's fingers and nipped between the finger tips so that the operator is able to move the needle holder element and needle together. The injection needle is thereafter inserted into the vein in the patient's arm by moving the needle holder element and needle forwardly in the axial direction of the needle. When the injection needle is thus inserted into the vein, the flexible side strip portions of the needle holder element are released from the finger tips and are allowed to resume their respective original positions projecting laterally from the rear end portion of the needle. When the side strip portions of the needle holder element assume these positions, the strip portions extend substantially in parallel with the surface of the patient's arm into which the injection needle is inserted and, thus, the needle holder element and accordingly the injection needle can be secured to the patient's arm by the use of, for example, and adjesive tape applied in part to the upper faces of the side strip portions of the needle holder element and in part to the surface of the patient's arm skin.
A scalp vein liquid injection device is thus adapted to secure an injection needle to that part of a patient's body into which the needle is inserted and is useful for proceding with medical administration or transfusion of blood for an extended period of time without constraining the subject to sit or lie in a fixed posture throughout the administration or blood transfusion.
The needle holder element of such a scalp vein liquid injection device serves not only as an anchor for the injection needle but as an aid in forcing the injection needle into a patient's vein. As the means to aid in inserting the injection needle into the vein, however, the needle holder element of the prior-art scalp vein liquid injection device has difficulties in holding the side strip portions of the needle holder element firmly and with certainty between finger tips and applying a proper concentrated force to the injection needle when in manipulating the needle holder element to insert the injection needle into the patient'vein. This is primarily because of the fact that the flexible side strip portions of the needle holder element are rather flimsy and small in construction and are inexpedient to handle.
When in inserting the injection needle of a scalp vein liquid injection device into a vein, furthermore, it is important to hold the injection needle correctly in a position in which the bevelled edge of the quillpen acuminated tip portion of the needle faces upwardly with respect to the upwardly facing surface of, for example, a patient's arm into which the injection needle is to be or has been inserted. In this instance, it is also important to have the needle holder element positioned so that the side strip portions thereof are to lie in parallel with the particular surface of the patient's arm skin when released from the finger pressure and allowed to resume their original positions and can thus be attached firmly and uniformly to the arm skin. For these purposes, not only meticulous care is required for correctly manipulating the needle holder element and needle during insertion of the injection needle into the vein but strict control over the positioning of the needle and the needle holder element to be assembled together and the quality of the resultant product during production of the scalp vein liquid injection device is indispensable.
If the injection needle fails to be inserted correctly and accurately into the desired vein by the first try, the physician (or nurse) would have to try to insert the needle into the vein repeatedly before the needle is successively inserted into the target vein, compelling the patient to suffer unnecessary pain. Such pain could however be precluded if the needle holder element of a scalp vein liquid injection device can be manipulated easily and assuredly when in inserting the injection needle into a patient's vein.
It is, accordingly, an important object of the present invention to provide an improved medical needle assembly or scalp vein liquid injection device which can be handled easily and assuredly when in inserting the injection needle into a patient's vein.
It is another important object of the present invention to provide an improved medical needle assembly or scalp vein liquid injection device which is provided with means adapted to enable the user of the device to insert the injection needle correctly and accurately into a target vein and to thereby banish the unnecessary pain which would otherwise be inflicted upon a patient when the injection needle can not successively be inserted into the target vein by the first try.
It is still another important object of the present invention to provide an improved medical needle holder assembly or scalp vein liquid injection device which requires no meticulous care for correctly positioning the needle and the needle holder element with respect to that portion of a patient's body into which the injection needle is to be inserted.
It is still another important object of the present invention to provide an improved medical needle assembly or scalp wein liquid injection device which can be manufactured without having recourse to exacting control over the relative position between the needle and the needle holder element to be assembled together and the quality of the resultant needle asssembly.
As will be understood more clearly as the description proceeds, it is still another important object of the present invention to provide an improved medical needle assembly or scalp vein liquid injection device in which the dimensions and weight of the needle holder element forming part of the needle assembly are reduced significantly so that the needle holder element can be secured to the patient's body skin by the use of an adhesive tape of a reduced size. When an adhesive tapes is attached to a body skin for an extended period of time, a rash tends to be produced on the skin by the poisoning effect of the adhesive compund. In the use of a medical needle assembly or scalp vein liquid injection device proposed by the present invention, such a problem can be to some extent alleviated because the needle holder element forming part of the needle assembly or scalp vein liquid injection device can be attached to the patient's body skin by the use of an adhesive tape of a significantly reduced size.